Torchlight II not only surpasses all expectations from the original Torchlight, it even rivals Diablo 3 and includes a multi-player cooperative campaign. The world is bigger, there are more bossess, minions, weapons, armors, classes, pet, locations, secrets... on and on and on...

There is actually more of everything! You will not be disappointed. In fact, it runs beautifully in PlayOnLinux too

When Steam is done installing the login screen will pop up. You probably won't see any text because there is a font bug.
Click the "X" to close Steam login

PlayOnLinux Shortcut

Select Steam.exe
Click Next

Name your shortcut: Torchlight II Steam
Click Next

Select "I don't want to make another shortcut"
Click Next

More PlayOnLinux Configuration

Back to PlayOnLinux
Click Configure
Select Steam virtual drive

General Tab
Arguments: -no-dwrite
This fixes the font problem

Note: -no-dwrite only works if you launch Steam from PlayOnLinux. Steam is automatically set to launch when Windows starts, which means if you do a "Windows Reboot" from the Wine tab -no-dwrite won't execute. Just close Steam and try again.

Wine Tab
Click "Windows reboot"
Close Steam because it will automatically launch when Windows reboots and won't execute -no-dwrite.

Close Configure

Launch Steam

Select Torchlight II Steam
Click Run

Click Login to an existing account

Login

Warning: Steam In-Game Community Overlay might need to be disabled to prevent crashing!

Installing Torchlight II

Select Torchlight II
Click Install

Click Next

Uncheck shortcut options
Click Next

Click Finish

Torchlight II is only a few Gigabytes
After its done downloading click Play

Note: Direct X and Visual C might start installing directly after the first installation. We have already installed these libraries, so just let it continue.

Launcher
Click the Play arrow

Optimization & Video Options

Click the wrench at the top right

There are a lot of video options and detail option to improve performance and an older computer or laptop.
I suggest setting the resolution to match your Linux desktop.
This way it appears to be fullscreen.

To improve performance you can:

Lower Particle Detail

Lower Shadow Detail

Disable Weather

Disable Anti-Aliasing

Disable VSync

Disable Rim Lighting

Disable Hardware Skinning

Disable Bloom

Try one at a time and launching the game to see if it made any difference.